Rubber heating unit



Sept. 1, 1936. M. MURPHY RUBBER HEATING UNIT Filed Nov. l2, 1934 /phyACL'ome/ys.

Patented Sept. l, 1936` aman HEATING UNrr Manon Murphy, Indianapolis,rnd.'

Application November 12, 1934, semi Np. 152,656 1 claim. (c1. zia-4s)This invention relates to electrical means for applying heat to variousparts of ones body. A primary object of the invention is to providemeans whereby an electrical heating element may be employed to be placedin close proximity to the skin without the danger of electrical burnsor' shock should the carrier of the element become wet or should theelement break within the carrier. Electrical heating pads have beenemployed for some time wherein the element was carried within some clothor. textile member and such a pad has become to be recognized asdangerous in that a slight molstening thereof places theelectricalcircuit in direct connection with the user and furthermore should thecircuit develop, there is great danger of fire. The heating element mustbe flexible in order to permit the pad to conform to the contour of thesurface to which it is applied and this means that the element issubjected to much bending which in itself tends to wear out the elementand cause it to break.

My invention consists essentially in embedding a resistance wire ofrelatively small diameter within rubber so that the element is at alltimes electrically insulated as well as being ventirely enclosed andcovered over against the entrance or access thereto of moisture. Bymeans of the rubber carrier, particularly in the form of a heating pad,the pad is exible so as to permit its conforming to the contour of thesurface over which it is'applied. Another advantage of my invention isthat it may be manufactured at a relatively low cost and still preservethe objects and advantages above indicated with perfect safety to theuser. f

Further objects and advantages of the invention will become apparent tothose versed in the art in the following description of the invention asillustrated by the accompanying drawing, in which Fig. 1 is a top planview of a pad embodying my invention with part of the upper sm'facebroken away; l

Fig. 2, a vertical transverse section on the line 2-2 in Fig. 1; A

Fig. 3, a front elevation of a pad embodying my invention in a modifiedform;

Fig. 4, a vertical transverse section on the'line 4--4 in Fig. 3;

Fig. 5, a top plan view of the form shown in Fig. 3;

Fig. fi, a vertical elevation in partial section of a heating unit forinternal use, and

Fig. '7 a transverse section on the line 1-1 in Fig. 6.

Like characters of reference indicate like parts throughout the severalviews in the drawing.

Referring first to the form of the invention as illustrated in Figs. 1and 2 showing a heating pad, I take a sheet I0 of uncured rubber andpress it down over a plurality o'f pins II. These pins Il are. properlylocated so that a length of resistance wire I2 may start by one end asat I 3 and then be carried therearound to form loops on one side of thecenter line and then carried across and around under those loops to theother side and looped back and forth to be carried around by its otherend I4 to terminate adjacent the first end I3. Conducting wires I5 andI6 are connected to the respective ends I3 and Il, these wires I5 and I6being preferably embedded and covered by rubber to form the customaryrubber insulated cable. This cable is so placed as to have the rubberinsulation thereof lapped over on the sheet l0 adjacent the wire ends I3and I4. I then -apply a second sheet of uncured rubber I1 over one tothe other to form in effect a resultant singie thickness of rubberwithin which the resistance wire I2 is embedded nearer one outer surfacethan the other.

The resistance wire I2 is preferably in a coiled form, although notnecessarily so. The coiled form is preferred on account of the fact thatit permits of a more exible pad and when the pad is folded or twistedaround, the wire itself is not so likely to break. The relativethicknesses of the sheets I0, I1 and I B as indicated in Fig. 2 aresomewhat exaggerated in the drawing in order to clearly show thestructure. overlaps the rubber4 insulation of the cable including thewires I5 and I6 so that the end of the cable is vulcanized between thesheets I0 and I1 to have its insulation become an integral part thereof.By reason of the single sheet I0 on one side and the two sheets I1 andI8 on the other side of the heating wire, the pad at once provides twoheats". That is on the side of the pad having but the one sheet I0covering the wire I2, more heat will be transmitted than on the otherside where two sheets cover the wire The sheet I 1 2 t. i2. 'Ihus bymerely turning the pad over, application of heat may be varied.

In the form of the invention as shown in Figs. 3-5, I have provided apad i9 here shown as hav- 5 ing a. marginal forwardly projecting ange 2twith a cable 2i leading from the center. The pad I9 is formed in thesame manner as above described .in reference to the pad shown in Figs. 1and 2 to have a heating element 22 embedded 10 within rubber. lThe pad'i9 is so formed as to proportions and dimensions that it may beinserted within a patients mouth to have the upper portion of the pad incontact with the upper teeth and gums and the lower part incontact withthe l5 lower teeth and gums. The pad in use assumes the shape somewhatas indicated by the dash lines in Fig. 5, they pad being suicientlyexible and elastic to permit its being inserted between the the cheeksand the teeth. The marginal harige 2dserves to space the cheeks awayfrom the pad and thereby prevent undue heating or burning of thevcheeks, thus permitting without discomfort. an application of heat at atemperature well above body heat to the patients gums. Where heat is tobe applied internally, the resistance wire 2t. Figs. 6 and 7, may bewound about an uncured rubber core 2d and the'n a sheet ci uncuredrubber 25 wrapped therearound and vulcanized to the core t6 within asuitable mold so as to form. an integral rubber carrier with the heatingwire 23 relatively close to the outer surface. The

, rigidity of the unit is determined by the rubber mixture employed. l

It is to be seen that in any one of the above indicated forms which areonly a few of the possible many forms the invention may assume, the

heating element is directly embedded within a rubber carrier to have theelement close to at least one side thereof, but thoroughly insulated 40against moisture as well as electrically so that the pad er neungunitwin be used in perfect safe- `ty under all conceivable conditions. Ind that by properly proportioning the heating element in the variousunits, I can secure a transmission of heat of desired amount without inany way aiecting the rubber carrier. It is of course essential to havea. suihcient amount vci. wire in the heating element so that no localarea thereof becomes heated to that temperature which will damage thesurrounding rubber. The heating element is directly embedded within therubber without any intervening fabric or other insulating medium. Sincethe cable leading the conducting wires from 'the heating unit is moldedand vulcanized in the unit to become an integral part thereof, there isno danger of break-down or water leakage at the connection of the cablewith the unit. y

While have herein shown and described my invention in the form now bestknown to me, itis obvious that structural changes may be made withoutdeparting from the spirit of the invention and I, therefore. do notdesire to be limited to that precise form beyond the limitations as maybe imposed by the following claims.

i claim: .a exible elastic heating pad comprising a length oi spirallywound resistance wire looped between two sheets of rubber vulcanized oneto the other to '.,iftend between the spiral windings and loops of thewire, said wire being in direct contact with the rubber and stretchingtherewith by reason of said spirally wound arrange ment, said wire beingwrapped around a plurality ci pins located so that a length of wirestarts at one end of the pad and is carried thence around forming loopson one side ci the center line of the pad and then carried across thepad under these loops to the other side of the pad and looped backandforth to form loops on 'the other side of the center line of the padand terminating adjacent the iirst end.

Q MORTON MURPHY.

